Lined gate valve



United States Patent [72] lnventor Lloyd E. Gustafson [56] References Cited Sl- Child, Mmmm uNrrED STATES PATENTS [2l] APP N' 738347 1,981,825 11/1934 Miner 137/375 [22] ed 5'1" 19'1968 3,217,739 11/1965 Lavauey etal 137/375 [45] Patented Ds 197 Re24 735 11/1959 williams 251/326 [73] Assignee Dm'i" C"P" 3 081'974 3/1963 Trau: 2st/328x SamnMinnesota Pnmary Examiner-Henry T. Klinksiek Attorney-Wolfe, Hubbard, Leydig, `v/ot & Osann [54] LINED GATE VALVE 2 Claims, 3 Drawing Figs. [52] U.S. Cl 137/375, ABSTRACT: A lined gate valve comprising a cast body hav- 251/328 ing a sleeve passage, and a throat passage in perpendicular [5l] l|1tfl F16k 27/00, alignment with the sleeve passage. The valve further com- Fl6k 3/02 prising preformed. corrosion-resistant throat and sleeve liner [S0] Field ofSeareh 137/375; sections contiguous with and supported by the inner surface 251/326-329 of the body material.

PATENTED nic 8 59m 1 LINED GATE vALvE This invention relates to gatefvalves, and in its principal ithe valve entirely from corrosion-resistant material, such as stainless steel, butsuch a construction is uneconomically difficult and expensive. On the other hand, easily worked and inexpensive conventional metal body materials such as cast iron must be furnished with a lining or coating of some kind if the desired corrosion resistance is to be achieved.

Previous valve designs have used either a heavy self-supporting fabricated `corrosionresistant liner, or alternatively a thin corrosion-resistant material backed by a heavier load bearing structure with a layer of deformable material sandwiched therebetween. Both of these techniques have disadvantages. The heavier, self-supporting lining is costly and makes inefficient use of the lining materials which are expensive and often difficult toworkln the alternative construeV tion, having a thinner lining material, the use of a deformable backing material has been necessary to allow the lining to conform to the generally uneven surface of the cast valve body. Lead and plastic materials have been used as backing for the thin linings, but these materials introduce temperature restric tions to the uses to which the valve may be put.

ln view of the foregoing, it is a principal object of the present invention to provide a-new and improved method of gate valve construction, as well as a gate valve of improved design in which relatively thin shells of corrosion-resistant lining material may `be utilized without the need to use deformable backing materials and without loss of strength.

lt is also' intended 4to provide an improved gate valve construction in which no operating adjustments are needed after assembly to assure pos'itivealignment of the gate with its seat.

A further object is to provide'a valve construction in which a series of valves may be easily provided from a single basic valve body unit. In this manner anentire line of valves having different pressure ratings may be produced from a single basic FIG. A1 is an exploded perspective view of a gate valve body unit exemplifying the present invention; FIG. 2 is a vertical section of a completed gate valve utilizing the bodyofFlG. lgand FIG. 3 is a partial section similar to FIG. 2 illustrating the action of a milling cutter in finish machining the valve seat.

Turning first to FIG. l, there is shown in exploded form a valve body unit constructed according to the present invention. The entire assembly is contained within a cast valve body f l0 having opposed, flat flanges with parallel attachment faces 11, 12 and which are provided with threaded bolt holes 13 for attachment purposes. At the top, additionalcast flanges l5, 16 are provided having holes 17 for the attachment of a valve su perstructure and actuating lrneans(not shown), and a gland or follower 18 (FIG. 2).

The valve lining is madel up of preformed sections of corrosion-resistant sheet material. The throat passage of the valve which communicates between the attachment faces 11, l2 is lined with a rst throat liner section half 21 and a second throat liner section half 22, each having a peripheral flange extending outward and overlying its respective attachment face vll, l2. These liner flanges are sandwiched within the joint between the valve body `l0 and similar flanges (not shown) on the pipes to which the valve is to be assembled. The sleeve passage, which lies perpendicular to the throat passage and which later receives a sliding gate 23, is lined with a stepped upper sleeve liner section consisting of an enlarged upper portion ZSQand a lower portion 26 having a semicircular cutout adapted to fit corresponding gate notches in each of the throat sections 21, 22. The joint between the latter members is backed up by a `semicircular backing strip 27 underlying the line of connection between the throat sections 21, 22, and wrapping about these sections to'meet the lowermost edges of the lower sleeve section 26.

The remaining elements of the completed valve body unit include a preformed annular valve seat 28, gate guiding and retaining blocks 30, and gate stops: 3l. Packing 32 (FIG. 2), which is retainedand compressed by the follower 18 within the upper sleeve section 25 in the vusual manner, is added to complete the gate valve.

Pursuant to a principal feature of the invention, the valve construction of the present invention allows the lining of thin corrosion-resistant sheet material ,to be completely contiguous j with the material of the cast valve body l0 throughout the entire inner surface area of the latter member. This is accomplished by rst casting the valve body` 10 with its sleeve passage being formed by a single casting core. The sleeve opening is thus smoothly finished and dimensionally accurate without parting lines or other surface defects. The throat vpassage is also cast with `a similar core or cores, but need not be made as accuratelyor withthe same degree of as-cast surface finish as the sleeve passage. As provided forby the invention, the smoothly cast sleeve passageis thereafter used as a reference from which the remaining finished portions of the valve body are located for final machining.

i As a next step in the manufacturing process, the cast body 10 is positioned for machining ofthe throat passage in perpendicular alignment relative to its cast sleeve passage. The remaining finished surfaces, including the attachment surfaces 11, 12 are then machined, using either the cast sleeve passage i or the now-finished throat passage for positional reference. The various `attachment holes 13, ``17 are desirably added at this time. Also machined is a circumferential slot 33 which will receive the backing strip 27.:

With the machiningv ofthe body casting 10 completed, the preformed liner sections areI assembled. The sheet metal sleeve liner section is assembled from. its upper and lower components 25, 26 prior to' assembly. Both it and the first and second throat sections 2l,` 22 are preferably stamped from sheet material. The two portions of the throat liner 21, 22, the backing strip 27 and the sleeve liner subassemblyare then assembled to one another and to the body 10. While fabrication by welding is most desirable in the case of sheet material liners of stainless steel or the like, `it will be appreciated that other fabrication techniques such as heat bonding and solvent welding may be used for other liner materials such as plastic. The throat passage having been vlinish machined into alignment with the sleeve passage, thethroat liner sections 21, 22 are thus allowed to t intimately against the body material and are substantially contiguous therewith over the entire throat area.

As the next step in fabrication, the preformed annular valve seat 28 is attached to its respective throat liner section 22, by

welding to the liner section l22 orby other suitable ineans. To

provide accurate seat alignment and as another feature of the invention, the valve seat 28 is intentionally made oversize with its gate-engaging face being unfinished. After assembly, the face is machined a distance A (FIG. 3) by a milling cutter 35 which is inserted from the opposite side of the valve body 10. The finishing cut on the face of the valve seat 28 is made with the now-lined body oriented Vin alignment with the sleeve passage in the same manner as was done in machining of the throat passage prior to assembly of the throat liner sections 21, 22. This technique causes the valve gate-engaging portion of the seat 28 to be precisely aligned with the sleeve through which the gate 23 will later be inserted. Thus it may be seen that no further alignment of the gate 23 after assembly is necessary, and the need for the adjustment apparatus commonly employed in previous gate valves is thereby eliminated. i

As an alternative procedure, the valve seat 28 may be finish machined prior to assembly, and then located with respect to an inserted gate 23 prior to welding theseat in place. ln this case, as with the technique in which the valve seat 28 is` after the gate 23 has been vassembled in place, thereby assuring the alignment and rigidity of ,these elements after assembly.

' Asi a principal advantage ofthe invention, it will be seen that a range o f gates of varying-.thickness and pressure capabilities may be utilized within the 'same ybasic valve body unit merely by varying the depth of theut made on the valve seat 28 by the milling cutter 35, drnins'talling the seat in a different axial positionf'lf a relatively thick gate 23 is to be used, the seatis cut back or'shiftedja greater distance to accommodate the increased width,k In this way any thickness ofvalve gate 23 can be centered vtfithiny itssleeve, and no adjustment means is necessary'.

1 It may be seen that a valve constructed according to the present invention enjoys the advantages of having the flow passage and sleeve passage contained within a single strong body unit. The packing chambenvbeing cast with single core,

` can be `lined with a suitable stepped liner section without further 'machining because o f Ithe dimensional accuracy achievable with such -a casting process. The corrosion-resistant liner Vmay be made as thin as desired in keeping with the technique of .fabrication used, and Ais` solidly backed over its entire area throughout the interior surfaces of the valve. The resulting valve uses a minimum ofthe relatively expensive corrosionresistant material while sacrificing nothing in strength. ln addition, no 4deformable backing material is required to add to the cost and complexity,oftheV valve, and which might introduce temperature limitations in use.

The use of a cast body in `combination with preformed sheet material liner sections allows a; choice of materials and combinations of materials which is greatly expanded over anything over previously possible in the gate valve art. All that is required is that the liner sections be bondable to one another, since it'isunnecessary that ,theyfbe bonded tothe valve body itself to withstand pressure forces'from within the valve. It is only necessary that'the liner section 22 which retains the valve seat 28 befsuiciently strong to resist pressure forces in the downstream direction when the valve is closed.

Variation of the valve construction to accommodate in creased pressure ratings requires only the use of a thicker gate 23. The body l0 is generally much stronger than any .gate which would be used in normalservice, and sinceithe line' material is backed up over its entire surface-by the body, the completed body unit is sufficiently strong for use with any vpractical thickness of gate 23 without change or additional reinforcement. The basictbody unit may thus be the same for all pressure ratings, providing considerable "economic adlplantages in producing a full range of valves of varying pressure ratings.

I claim: f 1 .Alined gate valve comprising, in combination: yavalve body having parallel attachment faces, a perpendicular sleeve opening, and a throat communicating between the attachment faces in perpendicular alignment with thesleeve opening;

a corrosion-resistant sheet material liner substantially icontiguous with the valve body over its internal surface, said liner consisting of connecting sections fabricated together to form a continuous f liner unit comprising a stepped upper sleeve liner section having an enlarged upper portion adapted to enclose a packing chamber, a connecting sleeve liner section, and first and second throat liner halves each having a integral peripheral flange adapted to overlie one attachment face of the valve body;

a slidable gate received within the lined sleeve opening `.for

entry into .the lined throat, and gate-packing means adjacent 'the sleeve;

an -annular seat attached to the inner periphery of the-lined `throat section and having agate-engaging face aligned with the sleeve opening for sealing engagementwith lthe gate; and

gate guiding and retaining means carried within the lined throat opposite the seat.

2. A lined gate valve as defined in claim l having a semcir cular backing strip underlying the line of connection between the throat liner halves and wrapping about the throat liner sections to meet the lower edges of the connecting sle'eve liner section. 

